It is known to allow for replacement of circuit boards in a system which employs such boards, such as a computer system, or to permit the addition of circuit boards to enhance the functionality of such a system. Typically, the system will try to use such circuit boards without verifying that they are compatible with the system.
It is desirable to permit the system to verify that a circuit board is compatible and may be used with the system. The goal in such a case is to ensure that the circuit board meets specifications for the system such as timing and power consumption. Such verification avoids placing correct system operation at risk due to an improperly designed circuit board.
In addition, such circuit boards are not uniquely identified in the system. Because such circuit boards may be interchangeably plugged into other ports within the system, or moved to other systems, the lack of a means of uniquely identifying such circuit boards prevents the system from maintaining an accurate history log for each circuit board. Such a log is useful in determining the source of errors which occur using a circuit board.
Further, it is desirable to accomplish such verification without the need to update the hardware on subsequent approvals of new versions of compatible circuit boards.
In addition, such verification signals are sometimes imitated or counterfeited. It is therefore desirable to provide an apparatus and method that enables only authentic circuit boards to function within the system and will prevent circuit boards with identical identifier signals from being used.